Field of the Invention
The present invention relates to a support plate that supports a wafer, a method for forming a support plate, and a method for processing a wafer by using a support plate.
Description of the Related Art
A semiconductor wafer on which a large number of devices such as ICs and LSIs are formed on the front surface and the individual devices are marked out by plural planned dividing lines (streets) formed into a lattice manner is processed into a predetermined thickness through grinding of the back surface by grinding apparatus. Then, the planned dividing lines are cut by cutting apparatus (dicing saw) and the semiconductor wafer is divided into the individual devices. The devices obtained by the dividing are widely utilized for various kinds of electronic apparatus such as mobile phones and personal computers.
The grinding apparatus that grinds the back surface of the wafer has a chuck table that holds the wafer and a grinding unit on which a grinding wheel having a grinding abrasive to grind the wafer held by this chuck table is rotatably mounted. The grinding apparatus can grind the wafer into a desired thickness with high accuracy. To grind the back surface of the wafer, the front surface side on which the large number of devices are formed needs to be held by suction by the chuck table. Therefore, normally a protective tape is stuck to the front surface of the wafer in order to prevent the wafer from being scratched (refer to e.g. Japanese Patent Laid-Open No. Hei 5-198542).
In recent years, electronic apparatus has a tendency toward smaller size and smaller thickness and semiconductor devices incorporated therein are also required to have smaller size and smaller thickness. However, when the back surface of a wafer is ground to reduce the thickness of the wafer to e.g. 100 μm or smaller, and furthermore to 50 μm or smaller, the rigidity significantly decreases and thus subsequent handling becomes very difficult. Moreover, warpage is caused in the wafer depending on the case and there is also a possibility that the wafer itself breaks due to the warpage. To solve such a problem, a wafer support system (WSS) is employed. In the WSS, the front surface side of a wafer is stuck to a rigid protective member by using an adhesive in advance and then the back surface of the wafer is ground to reduce the thickness of the wafer to a predetermined thickness (refer to e.g. Japanese Patent Laid-Open No. 2004-207606).